Development of RF transistors: a historical prospect

The development of RF transistors went almost unnoticed until the early 1980s because, unlike Si VLSI, there were no mass consumer markets for such devices. Most applications for RF transistors had been military oriented. Recently, this has been changed drastically due to the explosive growth of the markets for civil wireless communication systems. This paper covers the evolution and current status of transistors used in RF electronic systems. Important background, development and major milestones leading to modern RF transistors are presented. The concept of heterostructure, a feature frequently used in RF transistors, is discussed. The different transistor types and their figures of merit are then addressed. Finally an outlook of expected future developments and applications of RF transistors is given.